Ganged variable resistor

ABSTRACT

There is provided a ganged variable resistor comprising a cover having at least a bottom wall and a pair of side walls, a bearing mounted on the bottom wall of the cover, an actuating shaft rotatably supported by the bearing to extend therethrough, a plurality of bent portions formed on the sides of each of the cover side walls and arranged with some spacing therebetween to securely hold in place the insulating bases of a plurality of variable resistors at the respective stages, and a plurality of brushes mounted on the extension of the actuating shaft in such a manner that each of the brushes is slidable on the resistance element mounted on each of the insulating bases. The ganged variable resistor of this invention is advantageous in that the number of component parts is reduced to ensure simplified assembling operation and significant reduction in the thickness of the assembly.

United States Patent Matsui et al.

[ July 1, 1975 GANGED VARIABLE RESISTOR Primary Examiner-Bruce A.Reynolds Attorney, Agent, or Fi'rmStevens, Davis. Miller & Mosher [57!ABSTRACT There is provided a ganged variable resistor comprising a coverhaving at least a bottom wall and a pair of side walls, a bearingmounted on the bottom wall of the cover. an actuating shaft rotatablysupported by the bearing to extend therethrough. a plurality of bentportions formed on the sides of each of the cover side walls andarranged with some spacing therebetween to securely hold in place theinsulating bases of a plurality of variable resistors at the respectivestages and a plurality of brushes mounted on the extension of theactuating shaft in such a manner that each of the brushes is slidable onthe resistance element mounted on each of the insulating bases. Theganged variable resistor of this invention is advantageous in that thenumber of component parts is reduced to ensure simplified assemblingoperation and significant reduction in the thickness of the assembly.

6 Claims, 5 Drawing Figures l- 39 IO PATH 'TF. JUL 1 SHEET FIG.

1 GANGED VARIABLE RESISTOR The present invention relates to an improvedganged variable resistor wherein the number of the component parts isreduced and the assembling operation is simplilied to ensure asimplified assembly and significant reduction in the thickness of theassembly.

The invention will be described in greater detail with reference to theaccompanying drawings, in which;

FIG. 1 is a sectional view of a prior art ganged vari able resistor;

FIG. 2 is a sectional view of a ganged variable resistor according to anembodiment of the invention;

FIG. 3 is a perspective view showing the cover of the ganged variableresistor of FIG. 2 before the assembling thereof; and

FIG. 4 is a perspective view showing the extension shaft and the brushused in the ganged variable resistor of FIG. 2.

FlG. 5 is a view of a base of the ganged variable resistor of HG. 2.

In a known type of ganged variable resistor, as for example illustratedin FIG 1, the spacing between the respective variable resistors isprovided in such a manner that a cup-shaped metallic cover 2 of thepreceding variable resistor is secured, as by calking, to an insulatingbase I of the following variable resistor, and then the fitting legs(not shown) provided on the open end side of the preceding metalliccover 2 is secured. as by calking, to an insulating base 1' of thepreceding variable resistor (this may be the insulating base of the saidfollowing variable resistor).

With the construction described above. it is necessary to use as manymetallic covers 2 as there are variable resistors, and therefore it isdifficult to reduce the number of processing steps in the assemblingoperation. Another disadvantage of this prior art assembly is that anundesirably large spacing is required for the metallic cover 2 of thepreceding variable resistor so that the fitting legs on a metallic cover2' of the following variable resistor (this may be the metallic cover 2of the preceding variable resistor) may be bent and secured in place bycalking, and this is detrimental to the desired reduction in thethickness of the assembly.

In FIG. 1, numeral 3 designates an actuating shaft rotatably supportedby a bearing 4 to extend therethrough, 5 an extension shaft securelyconnected to the actuating shaft 3, 6 resistance elements mounted on therespective insulating bases 1 (1'). 7 brush holders mounted on theactuating shaft 3 and the extension shaft 5, 7 a brush holder formedintegral with the extension shaft 5 with brushes 8 fixedly mounted onthe brush holders 7 and the brush holder 7 in such a manner that each ofthe brushes 8 slides over the resistance element 6 in accordance withthe rotation of the actuating shaft 3. Numeral 9 designates contactsnormally in contact with the portion of the respective brushes 8, l0internal terminals to which the contacts 9 are secured by calking, 11intermediate bearings for securing, as by calking. the metallic covers 2(2') to the respective insulating bases 1 (1'). The external terminals(not shown) are brought out from the ends of the respective resistanceelements 6.

It is therefore an object of the present invention to overcome theforegoing difficulty.

In accordance with the present invention, there is thus provided a newand improved ganged variable resistor wherein the respective insulatingbases are held in place by a single common cover and the use of brushsupporting members heretofore used for fixedly mounting brushes iseliminated to reduce the thickness of the assembly and decrease thenumber of assembling operations.

Referring now to FlGS. 2 through 4, an embodiment of the presentinvention will be described.

In FIGS. 2 through 4, numeral 12 designates a metallic cover having anopen end and an open side. and a bearing 14 is secured, as by calking toa bottom wall 12a of the metallic cover 12 through a shield plate 13. Ametallic actuating shaft 15 is rotatably supported by the bearing 14 toextend therethrough. Numeral l6 designates an extension shaft of plasticmaterial which is not circular and which is securely connected to anupper end 17 of the actuating shaft 15 projecting into the cover 12, andthe extension shaft 16 is adapted to rotate along with the rotation ofthe actuating shaft [5. A brush holder 18 is formed integral with theextension shaft 16 at its lower end adjoining the upper end 17 of theactuating shaft 15. The extension shaft 16 and the actuating shaft 15may be made of plastic material as a single unit. Numeral l9 designatesa brush fixedly carried on the brush holder 18, and one end of the brush19 is in contact with a horseshoe resistance element 21 mounted on thelower surface of a rectangular insulating base 20 so that the end of thebrush l9 slides over the resistance element 21 as the brush holder 18 isrotated along with the rotation of the actuating shaft 15. A rotationstop extension 22 is formed as an integral part of the brush holder 18and this stop extension 22 engages a rotation stop projection 23 formedby cutting and raising a portion of a side wall 12b facing the open sideof the metallic cover 12 to limit the angle of rotation of the actuatingshaft [5. Numeral 24 designates a Contact secured to the lower surfaceof the insulating base 20 by calking an internal terminal 25 and thecontact 24 is normally in electric contact with the resistance element21. In this embodiment, the insulating base 20 is placed on inwardlyprotruding insulating base supports 26 formed by cutting and raisingportions of side walls 12c and 12d adjoining the open side of themetallic cover 12, and the upward movement of the insulating base isprevented by lower side tapered portions 27a of bent portions 27provided on the sides of the side walls 12c and 12d. In other words, theinsulating base 20 is securely held between the insulating base supports26 and the bent portions 27. The insulating base 20 is provided with acentral opening 28 through which the extension shaft 16 extends.

Numeral 29 designates a brush holder of metallic or plastic materialwhich is dish-shaped in section and which is mounted on the extensionshaft 16 to be positioned on the insulating base 20. Numeral 30designates a brush mounted on the extension shaft 16 by means ofafitting opening 30a so that it is placed on the brush support 29, andthe brush 30 is prevented from shifting in the direction of rotation ofthe extension shaft 16 by means of locking pawls 30b formed on the innerperiphery of the fitting opening 300 to fit in grooves formed on theouter surface of the extension shaft 16. Numeral 31 designates aninsulating base mounted on upper side flat portions 27b of the bentportions 27 formed in the side walls 12c and 12d of the metallic cover12, 32 a horseshoe resistance element in contact with one end of thebrush 30, 33 a contact similar in function with the contact 24, 34 aninternal terminal similar in function with the internal terminal 25.Similarly with the insulating base 20, the upward move ment of theinsulating base 31 is prevented by lower side tapered portions 35a ofbent portions 35 formed on the sides of the side walls l2c and 12d ofthe metallic cover 12 and spaced away from the bent portions 27 by somedistance. Numeral 36 designates an insulating base securely held betweenupper side flat portions 35b of the bent portions 35 and lower sidetapered portions 37a of bent portions 37, 38 an insulating base heldsecurely between upper side flat portions 371) of the bent portions 37and lower side tapered portions 39a of bent portions 39. In the likemanner as the insulating base 20, the insulating bases 31, 36 and 38 arerespectively provided with central openings 40, 41 and 42 through whichthe extension shaft [6 extends. Numerals 43 and 44 designate brushholders similar in function with the brush holder 29. Numerals 45 and 46designate brushes, 47 and 48 horseshoe resistance elements, 49 and 50contacts, SI and 52 internal terminals all of which function in theabove-described manner. Numeral 53 designates a metallic Cover mountedon the open end of the metallic cover 12.

in this embodiment, the external terminals (not shown) are brought outfrom the ends of the respective horseshoe resistance elements 21, 32, 47and 48. Further, the side walls 126 and 12d of the metallic cover [2 arerespectively provided with an inwardly protruding positioning projection54 extending in the same direction as the extension shaft 16, and thepositioning notches 60 formed on the edges of the insulating bases 20,3!, 36 and 38 are fitted on the positioning projections 54 to preventthe movement of the insulating bases 20, 31, 36 and 38 in the horizontaldirection.

The ganged variable resistor described above is assembled in thefollowing manner. Firstly, the metallic cover 12 and the bearing 14 arebrought together after which the actuating shaft is rotatably fit in thebearing 14 through lubricating oil and the extension shaft 16 issecurely connected to the upper end 17 of the actuating shaft 15. Inthis condition, the bent portions 27, 35, 37 and 39 formed on the sidewalls 12c and 12d of the metallic cover 12 have not been bent as yet.After the insulating base equipped with the resistant element 2], thecontact 24 and so on has been placed on the insulating base supports 26formed in the side walls 126 and lZd, the bent portions 27 are bent tosecurely hold the insulating base 20 in place. In this case, thepositioning notches formed on the edges of the insulating base 20 arefitted on the positioning projections 54 to place the insulating base 20on the insulating base supports 26. Thereafter, the brush holder 29 ismounted on the extension shaft 16 so that it is positioned on theinsulating base 20, and then the locking pawls 30b are fitted in thegrooves 161: to mount the brush 30 on the extension shaft l6.Thereafter, the insulating base 3] is placed on the upper side flatportions 27b of the bent portions 27, and then the bent portions 35 arebent to securely hold the insulating base 31 in place. Then, the similaroperations as described in connection with the insulating base 20 arecarried out. The similar process 15 repeated with the insulating bases36 and 38, and F1 rally the upper cover 53 is mounted in place.

While, in the embodiment of this invention described lbOV. the brushes33, 4S and 46 are respectively nounted through the brush holders 29, 43and 44 on those portions of the extension shaft 16 above the insulatingbases 20, 3] and 36, the brushes 33, 45 and 46 may be respectivelydirectly carried on the insulating bases 20, 31 and 36. Further, it ispossible to use plastic covers of sufficient strength in place ofmetallic covers. Further, it is sufficient if the metallic cover 12comprises at least the bottom wall and a pair of opposed side walls l2(and 12d, and the side wall 12b may be eliminated if a rotation stoppingmechanism is separately provided. Furthermore, while, in the embodimentdescribed above, the insulating base 20 is placed on the insulating basesupports 26, it may be placed on the similar bent portions as the bentportions 27, 35, 37 and 39.

What we claim is:

1. An improved ganged variable resistor assembly including a pluralityof variable resistors, wherein the improvement comprises a cover memberhaving at least a bottom wall and a pair of side walls, an actuatingshaft supported by and extending through a bearing provided on saidbottom wall, said actuating shaft including an extension, a plurality ofbent portions formed on the sides of each of said side walls andarranged at predetermined intervals to securely hold the insulatingbases of said plurality of variable resistors in place, and a pluralityof brushes mounted on said extension of said actuating shaft wherebyeach of said brushes is slidable on the associated one of resistanceelements provided on said insulating bases.

2. A ganged variable resistor assembly according to claim 1, whereinsaid bent portions on said cover member are arranged and bent inwardlyso that eachof said insulating bases is positioned by an upper side flatportion of said bent portions and is secured by a lower side taperedportion of a proceeding bent portion associated with each of saidinsulating bases.

3. A ganged variable resistor assembly according to claim 1, whereinsaid brushes each slidable on the resistance element mounted on each ofsaid insulating bases are directly mounted on an extension shaft of aplastic material which is placed on said extension of said actuatingshaft and whose section is not circular, and each of said brushes issupported by the associated one of said insulating bases.

4. A ganged variable resistor assembly according to claim I, whereineach of said pair of side walls of said cover member is provided with aninwardly protruding positioning projection extending along said pair ofside walls in the same direction with said extension of said actuatingshaft, and each of said insulating bases is provided with positioningnotches formed on the both edges of each of said bases to receive saidpositioning pro ections.

5. A ganged variable resistor assembly according to claim 3, whereinsaid cover member further includes a side wall provided with a rotationstop projection in addition to said pair of side walls, said extensionshaft is provided with a brush holder at that portion thereof adjoiningsaid bottom wall of said cover member, and said brush holder is formedas an integral part thereof with a rotation stop extension to engagewith said rotation stop projection to limit the angle of rotation ofsaid ac tuating shaft.

6. A ganged variable resistor assembly according to claim 3, whereineach of said brushes is supported by the associated one of saidinsulating bases through brush holding means.

1. An improved ganged variable resistor assembly including a pluralityof variable resistors, wherein the improvement comprises a cover memberhaving at least a bottom wall and a pair of side walls, an actuatingshaft supported by and extending through a bearing provided on saidbottom wall, said actuating shaft including an extension, a plurality ofbent portions formed on the sides of each of said side walls andarranged at predetermined intervals to securely hold the insulatingbases of said plurality of variable resistors in place, and a pluralityof brushes mounted on said extension of said actuating shaft wherebyeach of said brushes is slidable on the associated one of resistanceelements provided on said insulating bases.
 2. A ganged variableresistor assembly according to claim 1, wherein said bent portions onsaid cover member are arranged and bent inwardly so that each of saidinsulating bases is positioned by an upper side flat portion of saidbent portions and is secured by a lower side tapered portion of aproceeding bent portion associated with each of said insulating bases.3. A ganged variable resistor assembly according to claim 1, whereinsaid brushes each slidable on the resistance element mounted on each ofsaid insulating bases are directly mounted on an extension shaft of aplastic material which is placed on said extension of said actuatingshaft and whose section is not circular, and each of said brushes issupported by the associated one of said insulating bases.
 4. A gangedvariable resistor assembly according to claim 1, wherein each of saidpair of side walls of said cover member is provided with an inwardlyprotruding positioning projection extending along said pair of sidewalls in the same direction with said extension of said actuating shaft,and each of said insulating bases is provided with positioning notchesformed on the both edges of each of said bases to receive saidpositioning projections.
 5. A ganged variable resistor assemblyaccording to claim 3, wherein said cover member further includes a sidewall provided with a rotation stop projection in addition to said pairof side walls, said extension shaft is provided with a brush holder atthat portion thereof adjoining said bottom wall of said cover member,and said brush holder is formed as an integral part thereof with arotation stop extension to engage with said rotation stop projection tolimit the angle of rotation of said actuating shaft.
 6. A gangedvariable resistor assembly according to claim 3, wherein each of saidbrushes is supported by the associated one of said insulating basesthrough brush holding means.